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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: a) 4* (2*x +7)-3*(3*x-2)=24 b) -(38-x) – (-13 – x )=-31

Toán Lớp 6: a) 4* (2*x +7)-3*(3*x-2)=24
b) -(38-x) – (-13 – x )=-31

Comments ( 2 )

  1. Giải đáp:
     $a) 4.(2.x+7)-3.(3.x-2)=24$
    $⇒ 8x+28-9x+6=24$
    $⇒ (8x-9x)+(28+6)=24$
    $⇒ -x+34=24$
    $⇒ -x= 24-34$
    $⇒ -x=-10$
    $⇒ x=10$
    $vậy$ $x=10$
    $b) -(38-x)-(-13-x)=-31$
    $⇒ -38+x+13+x=-31$
    $⇒ 2x-25=-31$
    $⇒ 2x= (-31)+25$
    $⇒ 2x=-6$
    $⇒ x= (-6):2$
    $⇒ x=-3$
    $vậy$ $x=-3$
     

  2. a)4.(2x+7)-3(3x-2)=24
    =>4.2x+4.7-3.3x+3.2=24
    =>8x+28-9x+6=24
    =>(8x-9x)+(28+6)=24
    =>x(8-9)+34=24
    =>-1x=24-34
    =>-x=-10
    =>x=10
    Vậy x=10
    – Áp dụng : Tính chất nhân đơn thức với đa thức : a(b+c)=ab+ac
    b)-(38-x)-(-13-x)=-31
    =>-38-(-x)-(-13)+x=-31
    =>-38+x+13+x=-31
    =>(-38+13)+(x+x)=-31
    =>-25+2x=-31
    =>2x=-31-(-25)
    =>2x=-6
    =>x=-6:2
    =>x=-3
    Vậy x=-3

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222-9+11+12:2*14+14 = ? ( )

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